keys: relying on the type system to ensure keys are 32 byte arrays

src/identity/mixnet.rs

@@ -23,11 +23,11 @@ impl KeyPair {
         KeyPair { private, public }
     }
 
-    pub fn private_bytes(&self) -> Vec<u8> {
-        self.private.to_bytes().to_vec()
+    pub fn private_bytes(&self) -> [u8; 32] {
+        self.private.to_bytes()
     }
 
-    pub fn public_bytes(&self) -> Vec<u8> {
-        self.public.to_bytes().to_vec()
+    pub fn public_bytes(&self) -> [u8; 32] {
+        self.public.to_bytes()
     }
 }

src/persistence/pemstore.rs

@@ -52,10 +52,10 @@ impl PemStore {
         );
     }
 
-    fn write_pem_file(&self, filepath: PathBuf, data: Vec<u8>, tag: String) {
+    fn write_pem_file(&self, filepath: PathBuf, data: [u8; 32], tag: String) {
         let pem = Pem {
             tag,
-            contents: data,
+            contents: data.to_vec(),
         };
         let key = encode(&pem);